function y = computeGe(element,xi)
l = element.crackLength;
A = element.area;
n = element.normal;
if strcmp(element.mode,'constant')
    % y = -l/A*[n(1) 0;0 n(2);n(2) n(1)];
    y = -l/A*[n(1)^2 -n(1)*n(2);...
        n(2)^2 n(1)*n(2);...
        2*n(1)*n(2) n(1)^2-n(2)^2];
elseif strcmp(element.mode,'linear');
end
    %TODO
end
